Objects

• guest - visitor of the site, who is not registered
• user - users, who are registered on the site
• vendor - usually an online shop, where coupons can be applied
• coupon - usually a discount code with expiration date, either in absolute value (e.g. $10) or as percentage (e.g. 10% off). Sometimes it has a minimal order value, which should be reached to apply the coupon.